Fiber optic connectors are used to terminate the ends of fiber optic cables. There are many different fiber optic connector types. Example types of fiber optic connectors include FC-type, SC-type, ST-type and D4-type.
A typical connector includes a ferrule located inside the connector. The ferrule is a relatively long, thin cylinder made of a material such as ceramic. Other materials such as metal or plastic can also be used to make the ferrule. The ferrule defines a central opening sized to receive a fiber of a given cladding diameter. An epoxy is typically placed into the opening prior to inserting the fiber to hold the fiber in place. The ferrule functions to align and center the fiber, as well as to protect it from damage.
It is desirable to minimize the loss of signals passing through the fiber. Parameters for evaluating the performance of a connector include insertion loss and return loss. Insertion loss is the measurement of the amount of power that is transferred through a coupling from an input fiber to an output fiber. Return loss is the measurement of the amount of power that is reflected back into the input fiber. To enhance signal quality and therefore optimize insertion/return loss, it is desirable to inspect each connector during manufacture.